Round heart disease (RHD), a presumed viral myocarditis of turkeys, has been found to resemble hemodynamically congestive cardiomyopathy of humans. The radioactive microsphere technique for measurement of regional myocardial blood flow using microspheres of 15 microns or less in size will be used to systematically study regional myocardial blood flow in anesthetized closed chested turkeys with acute and chronic myocarditis, turkeys which have recovered from the disease and normal control turkeys of the same age, sex and flock. It is intended to determine whether regional blood flow abnormalities are present in any or all stages of the disease and thereby to define the role of regional myocardial blood flow abnormalities in the pathogenesis of this disease. The effect of drugs known to alter regional myocardial blood flow or having an anti-inflammatory action (hypertonic mannitol, nitroglycerin and corticosteroid hormones) will be evaluated at appropriate stages of the disease utilizing sequential microsphere injections. BIBLIOGRAPHIC REFERENCES: Einzig, S., Leonard, J. J., Lucas, R. U., Jr., Gerasch, D. A., Noren, G. R., Tripp, M. R., and Fox, I. J.: Organ blood flow and microsphere shunting in the turkey. The Physiologist 19:178, 1976.